How to wire up data context in modular application? - mvvm

Question

I am writing an application, WPF, using PRISM. I'm new so apologies if this question is poor form:
I have a module that up to now has a user control for displaying a list of inspections. My module has entities written and a DbContext class to access DB. My question is where should this get initialsed and passed into my ViewModel???????
Shell XAML
<Window x:Class="ChargeMgm.Desktop.Shell"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:prism="http://www.codeplex.com/prism"
Title="EMS" Height="350" Width="525">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="auto"/>
<RowDefinition MinHeight="100"/>
<RowDefinition/>
</Grid.RowDefinitions>
<TextBlock HorizontalAlignment="Center"
VerticalAlignment="Center"
FontFamily="Calibri"
FontSize="16"
Foreground="SteelBlue"
Margin="5">Street Works Modules</TextBlock>
<Border BorderThickness="1" BorderBrush="SteelBlue" CornerRadius="3" Grid.Row="1" Margin="5">
<ItemsControl prism:RegionManager.RegionName="MainRegion"
VerticalContentAlignment="Stretch"
HorizontalContentAlignment="Stretch"/>
</Border>
</Grid>
</Window>
Bootstrapper class
class Bootstrapper : UnityBootstrapper
{
protected override System.Windows.DependencyObject CreateShell()
{
return new Shell();
}
protected override void InitializeShell()
{
base.InitializeShell();
App.Current.MainWindow = (Window)this.Shell;
App.Current.MainWindow.Show();
}
protected override void ConfigureModuleCatalog()
{
base.ConfigureModuleCatalog();
ModuleCatalog moduleCatalog = (ModuleCatalog)this.ModuleCatalog;
moduleCatalog.AddModule(typeof(DefectModule.DefectModule));
}
}
Module
public class DefectModule : IModule
{
private readonly IRegionManager regionManager;
private IUnityContainer container;
public DefectModule(IUnityContainer container, IRegionManager regionManager)
{
this.regionManager = regionManager;
this.container = container;
}
public void Initialize()
{
container.RegisterType<IDefectsView, DefectsView>();
container.RegisterType<IDefectsViewModel, DefectsViewModel>();
container.RegisterType<IDefectContext, DefectContext>();
var view = container.Resolve<IDefectsView>();
if(regionManager.Regions.ContainsRegionWithName("MainRegion"))
{
regionManager.Regions["MainRegion"].Add(view);
//regionManager.RegisterViewWithRegion("MainRegion", typeof(IDefectsView));
}
}
}

Answer 1

If you're using Unity then you're in luck. If you need it initialise you DB context then you can do something like this:
IModule implementation code (for your module)
// Create Module http://msdn.microsoft.com/en-us/library/ff648781.aspx
public class Module:IModule
{
private IUnityContainer _container;
public Module(IUnityContainer container,IRegionManager regionManager)
{
_regionManager=regionManager;
_container=container;
}
public Initialize()
{
_container.RegisterType<IView,View>();
_container.RegisterType<IViewModel,ViewModel>();
_container.RegisterType<IDBContext,DbContext>();
var view=_container.Resolve<IView>();
//Create Region http://msdn.microsoft.com/en-us/library/ff648829.aspx
_regionManager.Regions["MainRegion"].Add(view);
}
}
The above will register all of your view, viewmodel and dbcontext, resolve them and add them into a region. For the above to work I'm expecting the following:
public class View:IView
{
public View(IViewModel viewModel)
{
}
}
public class ViewModel:IViewModel
{
public ViewModel(IDbContext context)
{
}
}
Basically, I'm expecting your viewmodel to be injected into your View and your DB Context to be injected into your ViewModel using Constructor Injection.
BTW - the links in the code go to MS sites that will provide more background on Module creation and Regions. I've got one final link: This is a "Hello World" Prism app. It's for Silverlight but this is basically the same thing as a WPF app in terms of code structure so should be useful:Prism Hello World